In surface pumping of oil wells where the polish rod raises and lowers a string of sucker rods a mile or longer to pump oil to the surface the stress and stretch of the sucker rod string together with the weight of the oil raised by the strings have caused numerous problems due to the motion up and down of the long string of rods which when subjected to the weight of the oil causes a rubber band effect of stretching the rod string and over travel between both maximum raised and lowered condition. This problem has been appreciated by the prior art at least since 1946 in the two U.S. patents to Paule Noll et. al. Nos. 2,504,218 and 2,572,748 and even more recently by Robert G. James in 1971 as shown in his U.S. Pat. No. 3,782,117.
The fact still remains notwithstanding the presence of these teachings sucker rod strings are still frequently broken, requiring pulling, often fishing for the broken end, of a mile or more of sucker rod string which results in loss of production in the well, cost of pulling the rod string and its replacement which at least in part has been caused by rod stretch, over travel and an inadequate time period in a mechanical system to dampen out the oscillations in too quick a reversal in either up or down stroke.